Final answer:
The question contains a set S and provides values that are mistakenly referred to as probabilities for its elements. The correct option for P(a) based on the value provided is 8, although the values exceed the range of valid probabilities.
Step-by-step explanation:
The question presents a set S = {a, b, c} and provides the probabilities for two elements, specifically P(a) = 8 and P(b) = 7. We are asked to find P(a); however, there appears to be a confusion as probabilities cannot be greater than 1. This is likely a mistake, and we should consider the provided probabilities as weights or values rather than actual probabilities.
If they were probabilities, the question as written would be incorrect because probabilities must be between 0 and 1, inclusive.
Assuming that the values given for a and b are correct, the correct option for P(a) would thus be the one that matches the value provided for P(a) in the set, which is 8.
In summary, when giving the measure of probability for any event, it should be within the range of 0 to 1. Since the question does not align with the conventions of probability, the response is based on the assumption that the numbers provided are representative values and not actual probabilities. Therefore, the correct option for P(a) is 8.